Impedance characterization of high frequency power electronic circuits

Wide bandgap semiconductors as Silicon Carbide (SiC) lead to devices with smaller body capacitances and thereby support the continuous rise of operating frequency and switching speed of switch mode power supplies. However, parasitic elements coming from the real world setup gain more and more impact on system performance. In order to identify parasitic circuit components and corresponding resonances, this work is about small-signal impedance spectra measurements of power electronic circuits. Knowing the involved parasitics, destructive resonance phenomena can be avoided and electromagnetic radiation can be reduced. In order to include voltage drift effects of capacitive circuit elements, also impedance measurements with high voltage DC-bias were performed. For that, a broadband DC-blocker with 1 kV bias voltage rating was developed. Exemplary, two applications were investigated closer: a power semiconductor dynamic test circuit and an RF half-bridge inverter for the pulsed operation of dielectric barrier discharge (DBD) light sources.